Mounting means for moving shadow mask axially forward upon heating



June 1968 J. w. SCHWARTZ 7,

MOUNTING MEANS FOR MOVING SHADOW MASK AXIALLY FORWARD UPON HEATING FiledJan. 11, 1967 INVENTOR:

JAMES W. SCHWARTZ United States Patent MOUNTING MEANS FOR MOVING SHADOWMASK AXIALLY FORWARD UPON HEATING James W. Schwartz, Western Springs,Ill., assignor to National Video Corporation, Chicago, R1,, atcorporation of Illinois Filed Jan. 11, 1967, Ser. No. 608,561 3 Claims.(Cl. 313-85) ABSTRACT OF THE DISCLOSURE A quadrilateral shaped fittingfor mounting a mask in a color television tube, the fitting beingadapted to be distorted upon increase in dimension of the shadow maskrelative to the tube envelope so as to produce an axial movement of theshadow mask and thereby maintain the mask openings in register withelectron beams.

Summary of invention The usual color television tube making use oftriads of green, red and blue dots, has a shadow mask interposed in theelectron beam path closely adjacent the phosphor screen. Such a mask canchange in dimension relative to the usual glass envelope of the tube,particularly because of increase of temperature, and this repositionsthe abovementioned openings laterally of their original positionstherebybringing about a degree of misregister. I have solved this problem byproviding true compensation for'a change in size of the mask relative tothe envelope and implement this through using a parallelogram-likeconnection between the mask and the envelope which partially collapseson itself in a pivotal-type movement so as to reposition the mask closerto the phosphor screen and thereby maintains the mask openings inregister with the electron beams.

The invention is described in conjunction with an illustrativeembodiment in the accompanying drawing, in which- FIG. 1 is afragmentary sectional view of a portion of a color television tubeshowing the shadow mask mounted within the face plate;

FIG. 2 is a fragmentary sectional view of a portion of a tube,essentially that seen in FIG. 1, but enlarged relative thereto and partsthereof in a somewhat dilferent operational condition;

3,387,160 Patented June 4, 1968 opening of the spring clip 14. In theinventive arrangement, the opening 17 receives a portion of the post 12and provides the actual mounting of the mask on the face plate. However,as can be seen in FIG. 1, the opening 15 is concentric with the post 12and is adapted to engage a cylindrical portion 12a of the post 12 toprovide an additional mounting during times of extraordinary stress. If,for example, the tube is given a rough shock so as to unduly flex thefitting 16, the opening 15 provides a sup- FIG. 3 is a fragmentaryperspective exploded view of the tube parts seen in the foregoing views;and

FIG. 4 is an enlarged fragmentary perspective view of the lefthandportion of FIG. 3.

In the illustration given and with reference to FIG. 1, the numeral 10designates generally the glass envelope portion of a color televisiontube. More particularly, the envelope is seen in its face-plate portionwhich terminates at a lip 11 (see the upper righthand portion of FIG.1). The lip 11 is adapted to be fused to the funnel portion of thecathode ray tube (not shown). The face plate is equipped with aplurality of radially inwardlyextending posts as at 12 in FIGS. 1-3 andthese are provided for mounting the usual shadow mask 13.

Normally, the shadow mask 13 is supported on the posts 12 by means ofspring clips 14 which are weldably plemental engagement means with theposts 12 to additionally stabilize the mask 13 in place within the tube10.

The fitting 16 is constructed of relatively light metal (in comparisonwith the spring clip 14) and is seen to include a main body portion orpanel 18 about the opening 17 integrally coupled to laterally-extendinglegs 19 and 21, the legs 19 and 21 in turn being equipped with integralflanges as at 20 and 22 which are weldably secured to the associatedspring clip 14. The spring clip 14 is equipped with an abutment means inthe form of boss or projection 23 which is adapted to engage aconfronting surface of the mask 13.

Operation The operation of the invention can be best understood from acomparison of FIGS. 1 and 2. In FIG. 2, the numerals applied to partswhose position has changed from that in FIG. 1, are differentiated fromthe corresponding numerals in FIG. 1 by the addition of a prime Thus,for example, the shadow mask is designated 13' in FIG. 2 and it will beseen that the mask 13' is somewhat closer to the envelope 10 in FIG. 2than it was in FIG. 1 (taking into account the difference in scale).Normally, this occurs because the heatup of the mask 13 is greater thanthat of the envelope 10. For example, the shadow mask may increase intemperature about 30 C. while the glass envelope 10 increases only 10 C.in normal operation. The lateral expansion of the mask 13 (to thecondition designated 13' in FIG. 2) brings the frame 24 of the mask intoengagement with the inner end of the abutment 23 (as can be appreciatedfrom the designations 23 and 24' in FIG. 2). The engagement of theabutment 23 with the mask 13 results in partially collapsing ordistorting the fitting to that shown at 16' in FIG. 2, particularly inthe area designated 25.

It will be seen that the main body portion 18 is related to theconnective portion 19 by a smaller acute angle in FIG. 2 as compared tothat in FIG. 1. Thus the quadrilateral originally defined by the spring14, legs 19 and 21, and body portion 18 is partially collapsed ordeformed to that shown in FIG. 2 and defined by the parts 14', 19' and21, and 18' respectively.

It will be appreciated that the movements encountered and employed areof a relatively small order of magnitude. The expansion of the shadowmask is in terms of a few thousandths of an inch and to compensate forthis lateral movement, it is only necessary to advance the mask axiallytoward the phosphor screen a correspondingly small distance. A moredetailed explanation and showing of this activity can be seen in theco-owned, co-pend ing application of James W. Schwartz and Laslo JavorikColor Television Tube Mask Mounting.

It will be appreciated that the inventive construction provides a trulyselective repositioning of the shadow mask 13 axially of the tube incontrast to other techniques which are temperature-dependent. Althoughthe inventive construction does respond to changes of temperatureinteriorally of the tube, such changes can be eifective to repositionthe mask only if these temperature changes result in a change in size ofthe mask relative to the envelope. If, for example, the envelope were tochange in size correspondingly, no movement .of the mask would occurwhen the inventive construction is employed. On the other hand,constructing the mounting of temperatureresponsive materials couldresult in a repositioning of the mask when none is desired, i.e., wherethe original relationship between the mask and the screen is preserved,notwithstanding change in size.

By providing the generally cylindrical portion 12a of the post 12, Iinsure that upon contact of the spring clip 14 (in the area of theopening 15) with the post 12, there is a firm seating against anyextraordinary stress which might tend to otherwise dislodge the maskfrom its proper mounting on the associated posts.

While in the foregoing specification a detailed descrip tion of anembodiment of the invention has been set down for the purpose ofexplanation, many variations of the details herein given may be made bythose skilled in the art without departing from the spirit and scope ofthe invention.

1 claim:

1. A color television tube comprising an elongated envelope with anenlarged faceplate panel at one end and a phosphor pattern deposited onthe interior of said faceplate panel defining a viewing screen, aplurality of mounting posts embedded in a peripheral flange of saidfaceplate panel and extending radially of said tube, an apertured shadowmask, a frame about said mask of rigidly supporting the same, resilientmounting means on aid frame for each of said posts adapted for limitedmovement inward of said frame, a distortable member having first andsecond legs attached to said resilient means and inclined outwardly andrearwardly therefrom, and a panel integral with said legs and having anaperture for receiving an associated post, whereby as said mask andframe expand laterally due to heating, said resilient means iscompressed until limited, so that additional expansion causes furtherinclination of said leg members, thereby translating said mask forward.

2. The structure of claim 1 wherein each of said resilient meanscomprises a resilient, fiat mounting spring attached to said frame anddefining an aperture in line with the aperture of its associateddistortable member for also receiving its associated post; and anabutment mounted between said frame and said spring for limiting inwardmotion of said spring.

3. The structure of claim 2 in which said distortable member has twolegs thereof arranged generally parallel to each other with the panelinterconnecting said legs and the edges of said legs remote from saidpanel being coupled to said resilient means, whereby a generallyparallelogram shape is provided, an opening in said panel receiving saidpost for mounting said mask thereon, the angular relation between saidpanel and said legs being variable to reposition said mask axially ofsaid tube.

References Cited UNITED STATES PATENTS 2,795,718 6/1957 Van Hekken etal. 3,330,980 7/1967 Shrader.

ROBERT SEGAL, Primary Examiner.

